The aim of this research will be to study the structure and function of human fibronectin. It has been clearly demonstrated by many reports that fibronectin plays an important role in cell adhesion processes. Cell adhesiveness is a fundamental cell property relating to many important physiological phenomena such as embryogenesis, morphogenesis, inflammation, wound healing, and malignancy. Understanding the mechanism of action of fibronectin in these phenomena will be considerably advanced with the knowledge of its chemical structure. This proposal is directed at solving the primary structure of fibronectin and initiating tertiary structure studies on the intact molecule as well as limited proteolytic fragments. The strategy for primary structural analysis will involve reducing the large fibronectin molecule into smaller fragments by limited enzymatic and chemical hydrolysis. A number of published studies have now shown that such fragments are readily obtained from fibronectin. Importantly, the various peptide fragments generated during amino acid sequence analysis will be thoroughly examined for biological activity to establish the precise amino acid residues involved in cell attachment, and binding to collagen, actin, fibrin, and glycosaminoglycans. In addition, carbohydrate structural analyses will be performed on small glycopeptides representing single attachments of carbohydrate moieties. Assignments of biological activities to specific structural regions will be further determined by probing the fibronectin molecule with specific chemical modification reagents as well as with monoclonal antibodies that we have already established. Studies are also proposed to determine the structural differences between plasma and cell surface fibronectin. The proposed studies will considerably advance our present understanding of the structure and function of human fibronectin and will provide precise localization of the various biological functions to the smallest definable region of primary structure and hopefully as well to tertiary structure.